Lifestyle behaviours, glucose management and diabetes awareness among Iranian population with diabetes: evidence from a nationwide study
Objective To investigate the association between a Composite Lifestyle Index (CLI) and glucose management among Iranian adults with diabetes and to assess the geographic distribution of lifestyle behaviours. Design Cross-sectional. Setting A population-based nationally representative survey conducted across all 31 provinces of Iran based on data from the 2021, the latest, WHO STEPwise Approach to Noncommunicable Disease Risk Factor Surveillance (STEPS) survey. Participants Adults aged ≥25 who completed the third step of the STEPS study and met one or more of the following criteria—fasting blood sugar (FBS) of 126 mg/dL or higher, haemoglobin A1c (HbA1c) of 6.5% or higher or current use of glucose-lowering medications. Finally, 3042 adults with diabetes were included in the analysis. Primary and secondary outcome measures A CLI was derived from diet, physical activity, smoking and alcohol consumption and categorised into tertiles representing the lowest, moderate and highest engagement in healthy lifestyle behaviours. Diabetes awareness was assessed by self-report, and suitable glucose management was defined as HbA1c <7%. Results In fully adjusted models, moderate lifestyle engagement was significantly associated with lower FBS (aß=−7.36, 95% CI −13.35 to −1.38, p=0.01) and lower HbA1c (aß=−0.27, 95% CI −0.46 to −0.07, p=0.00) compared with the lowest tertile. Additionally, improving the CLI from the first to second tertile was associated with 1.37 times higher odds of achieving suitable glucose management (p=0.01). Restricted cubic spline analysis confirmed a significant non-linear relationship between continuous CLI and both FBS (Pnon-linearity=0.002) and HbA1c (Pnon-linearity=0.005), with maximal glycaemic benefits observed at moderate CLI values. Conclusions The relationship between healthy lifestyle behaviours and glycaemic outcomes among Iranian adults with diabetes was non-linear, a U-shaped pattern. Glycaemic benefits peaked at moderate engagement levels, and diminished at the highest levels of engagement. These exploratory findings suggest that moderate lifestyle engagement may be associated with improved glycaemic outcomes, highlighting the need for prospective studies to evaluate whether integrating tailored lifestyle promotion into diabetes management can effectively benefit underserved regions.